Regular Expressions 101

Save & Share

Flavor

  • PCRE2 (PHP >=7.3)
  • PCRE (PHP <7.3)
  • ECMAScript (JavaScript)
  • Python
  • Golang
  • Java 8
  • .NET 7.0 (C#)
  • Rust
  • Regex Flavor Guide

Function

  • Match
  • Substitution
  • List
  • Unit Tests

Tools

Sponsors
There are currently no sponsors. Become a sponsor today!
An explanation of your regex will be automatically generated as you type.
Detailed match information will be displayed here automatically.
  • All Tokens
  • Common Tokens
  • General Tokens
  • Anchors
  • Meta Sequences
  • Quantifiers
  • Group Constructs
  • Character Classes
  • Flags/Modifiers
  • Substitution
  • A single character of: a, b or c
    [abc]
  • A character except: a, b or c
    [^abc]
  • A character in the range: a-z
    [a-z]
  • A character not in the range: a-z
    [^a-z]
  • A character in the range: a-z or A-Z
    [a-zA-Z]
  • Any single character
    .
  • Alternate - match either a or b
    a|b
  • Any whitespace character
    \s
  • Any non-whitespace character
    \S
  • Any digit
    \d
  • Any non-digit
    \D
  • Any word character
    \w
  • Any non-word character
    \W
  • Non-capturing group
    (?:...)
  • Capturing group
    (...)
  • Zero or one of a
    a?
  • Zero or more of a
    a*
  • One or more of a
    a+
  • Exactly 3 of a
    a{3}
  • 3 or more of a
    a{3,}
  • Between 3 and 6 of a
    a{3,6}
  • Start of string
    ^
  • End of string
    $
  • A word boundary
    \b
  • Non-word boundary
    \B

Regular Expression
No Match

/
/
gmi

Test String

Code Generator

Language

Generated Code

import java.util.regex.Matcher; import java.util.regex.Pattern; public class Example { public static void main(String[] args) { final String regex = "(?<type>.{1})(?<user_access>.{3})(?<group_access>.{3})(?<other_access>.{3}) +(?<oder>[0-9]*) +(?<owner>[a-z]*) +(?<group>[a-z]*) +(?<size>\\d*) +(?<month>[a-z]{3}) +(?<day>\\d{1,2}) +(?<year>\\d{0,4})(?<time>(?<hour>\\d{2}):(?<minute>\\d{2}))? +(?<filename>(?<basename>.+)\\.(?<extension>.*)|(?<no_extension_filename>.*))"; final String string = "total 80\n" + "drwxr-xr-x 2 root root 4096 Sep 23 15:20 bin\n" + "drwxr-xr-x 3 root root 4096 Sep 3 18:41 boot\n" + "drwxr-xr-x 3 root root 4096 Aug 19 20:48 build\n" + "drwxr-xr-x 14 root root 3900 Sep 23 15:20 dev\n" + "drwxr-xr-x 98 root root 4096 Sep 23 15:20 etc\n" + "drwxr-xr-x 4 root root 4096 Oct 6 2014 home\n" + "drwxr-xr-x 21 root root 4096 Aug 21 19:49 lib\n" + "drwxr-xr-x 2 root root 4096 Jul 8 13:21 lib64\n" + "drwx------ 2 root root 16384 Aug 26 2014 lost+found\n" + "drwxr-xr-x 2 root root 4096 Aug 26 2014 media\n" + "drwxr-xr-x 2 root root 4096 Apr 10 2014 mnt\n" + "drwxr-xr-x 2 root root 4096 Aug 26 2014 opt\n" + "dr-xr-xr-x 133 root root 0 Sep 23 15:20 proc\n" + "drwx------ 4 root root 4096 Sep 23 15:27 root\n" + "drwxr-xr-x 22 root root 760 Sep 23 17:40 run\n" + "drwxr-xr-x 2 root root 12288 Sep 23 15:20 sbin\n" + "drwxr-xr-x 2 root root 4096 Aug 26 2014 srv\n" + "dr-xr-xr-x 13 root root 0 Sep 23 15:20 sys\n" + "drwxrwxrwt 2 root root 4096 Sep 23 17:40 tmp\n" + "drwxr-xr-x 10 root root 4096 Aug 26 2014 usr\n" + "drwxr-xr-x 14 root root 4096 Aug 21 19:52 var\n"; final Pattern pattern = Pattern.compile(regex, Pattern.MULTILINE | Pattern.CASE_INSENSITIVE); final Matcher matcher = pattern.matcher(string); while (matcher.find()) { System.out.println("Full match: " + matcher.group(0)); for (int i = 1; i <= matcher.groupCount(); i++) { System.out.println("Group " + i + ": " + matcher.group(i)); } } } }

Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Java, please visit: https://docs.oracle.com/javase/7/docs/api/java/util/regex/Pattern.html